Hydraulic Seeding

By Glenn Young

You have probably driven down the highway or through neighborhoods and have seen that “green stuff” sprayed on dirt. The correct terms for it are hydromulch or hydroseed. Both names describe the same thing. The early equipment models for this process of covering dirt were Finn's “HydroSeeder” and Bowie's “HydroMulcher,” and these names stuck to generically describe hydraulic mulching. This process of hydraulic seeding consists of mixing mulch, seed, fertilizer, soil activators and glues, then spraying these onto the soil creating a seeding mat which, when watered several times a day, keeps moisture next to the seed for quick germination.

EQUIPMENT SELECTION

Today, there are many manufactures of hydraulic seeding equipment that span many price ranges depending on the size and type of equipment. The units range from 100-gallon to 3,000-gallon tanks; from jet agitation to mechanical agitation; from rotary pumps to gear pumps. So it can be overwhelming deciding what machine is best for you and your business.

Before you jump in to purchasing a hydraulic seeder, consider what type of work you plan to do. While some contractors perform highway work that often includes 50-acre jobs, most of us are seeding home lawns and doing small commercial work spanning, on average, 5,000 to 60,000 square feet. You will want to pick a machine that fits your needs in doing an average day's work.

One equipment option you'll need to decide on is jet agitation vs. mechanical agitation. Jet agitation is more limited when it comes to the amount of mulch you can add, as well as the type of mulch that works with the machine. Some models have more pressure and keep agitating while you are spraying; others have a weaker spraying power and do not agitate while spraying, allowing the mulch and seed to settle in the tank, giving uneven results. Jet agitation models are less expensive than mechanical agitation.

Mechanical-agitation not only performs hydroseeding, but also spreads BFMs (bonded fiber matrix) that require very thick slurry. These machines normally have stronger spraying power and can handle a bigger variety of jobs. They are more expensive, but built to last.

Because there are many differences in machines, it's essential that you test out any machine you are considering purchasing to see how well it loads and sprays before you buy it. The speed of loading and mixing is as important as how well it sprays. Realize that you may not get the footage out of the machine that the manufacture claims can be planted per load. If job soil conditions are right, with a thin mulch mix on an open field with an experienced installer who is not worried about what it looks like, it might result in the manufacturer-stated footages per load. But if you're doing quality work (many times under less-than-ideal conditions), it may require heavier mulch applications. For example, smaller homeowner jobs will require more material than a big, open area erosion-control job. If soils are wet, dry, sandy or clay, these conditions will alter the expected amount of footage per load.

MULCH

Mulch is the one ingredient that makes hydraulic seeding better than hand-seeding. It makes up the seeding bed that the seed germinates in, holds moisture next to that seed and holds it in place. You can choose traditional wood mulch or paper mulch. Both have improved over the years. With wood, fibers are much longer than the fibers in paper, and paper mulch has air pockets that make it float without agitation. Some paper manufactures are adding surfactants to allowing the paper mulch to stabilize in the mix. Some wood-fiber manufactures are adding polyacrylamide pellets to allow more moisture holding ability. The real test is what works best for you as far as the staying power during rain storms and germination.

POLYMERS: THE BEST PRODUCT SINCE MULCH

If you are not using polymer tackifiers (a linear cross-linked polyacrylamide, often called PAM or PIDG-PAM) in your hydroseeding mix, you are missing out. This has to be the one best improvement in the process over the years, contributing to our success of hydromulch applications. Polymers help retain moisture in your mulch and keep it in place as a tackifier and prevent “splashing.” After using it, your jobs will rarely wash and there is no need to clean up job sites. That alone will save hours of work a day cleaning up, allowing more time for new work and more profit.

In the past, no matter how careful you were, splashing the sidewalk, the driveway and at least 18 inches on the house were inevitable. Now, thanks to polymer tackifiers, you will barely splash the first brick. You can go right up to the sidewalk or driveway and barely get one inch of mulch on the concrete. Polymer tackifiers work by thickening the water to a syrup consistency, causing it to stay where you put it. This helps, because even though the products we are using do not stain, the dirt we are spraying does. I know of a contractor who had to replace a new wood fence because the black dirt, mixed with hydromulch, stained it 18 inches from the ground. Because our fertilizers can corrode an air conditioner unit splashed by our mulch, polymers allow you to be neater with overspray and keep it clean. Polymers are well worth the money.

Another application that involves polymers is to use them in combination with the old agar glue, creating a “super-glue” bonding to the soil. The old agar type tackifier is great, until it gets wet and then it has no holding power. But combined with the polymer, you create a moisture-holding, super-bond that really stays in place. Put it on twice as thick as your hydromulch, at 4,500 pounds per acre, and you have a “Poorman's Bonded Fiber Matrix.” I do not believe this works as well as the pre-packaged BFMs, but if you are not able to spend the money on the pre-packaged products, this is a way to hold your application in place no matter how steep the slope is.

The trick is to add enough polymers to be effective. Suppliers recommend the use of 3 pounds per acre, but this should be considered a minimum application. I was at first given a sample of 5 pounds to try and was told to use a couple of tablespoons to 500 gallons of water. At those amounts, I saw no holding power as a tackifier. I still had most of the 5 pounds left and was using my machine to settle the dirt on my freshly-graded road by spraying water on the dirt and driving on it to pack it down. I decided to throw the rest of the polymer into the water. When I walked past the machine several minutes later, 8 feet from the opening, I was splashed as if someone threw a 5-gallon bucket of water on me. I was puzzled at what had just happened. I looked into the machine and the water was so thick that chunks of it would turn loose and fly through the air in a glob. I realized it was a reaction to the polymer and decided more experimentation was needed.

I commonly use 1 pound per 1,000 square feet, and for extra holding power on steep slopes, I use 1.5 pounds per 1,000 square feet. To create the “Poorman's Bonded Fiber Matrix,” I use 2 pounds of polymer with 2 pounds of agar per 1,000 square feet added to the mulch at 4,500 pounds per acre. It is amazing to peel up a 12-inch X 12-inch sheet of the application and discover that it holds together. The polymers help bond the soil together and will absorb rain instead of letting it run down the slope.

It works its way into the soil, breaking down after six months and is harmless to the environment. There are no known Environmental Protection Agency (EPA) regulations as of yet and the USDA recommends its use. It is slippery when wet and you should warm customers to stay off mulched areas.

You can buy polymers under several names from most suppliers and prices range from less than $3 to more than $12 per pound. There are variations in this product, so be aware of which type you're purchasing.

NEW PRODUCTS

New gear pump

If you already own a hydroseeding unit, you can make upgrades by researching the latest technology and products. The TurfMaker Corporation produces a patented gear pump that is affordable and does not catch and hold unwanted mulches that causes deterioration, increasing the life of the equipment. They have improved the rotary gear pump, and you can use it to replace the pumps on many other brands of hydroseeding equipment.

A rotary gear pump is preferred for pumping thick slurries through long hoses. This type of pump also requires substantially less horsepower than centrifugal pumps. The rotary gear pump improvements extend the useful life of rotary gear pumps substantially. These improvements include a hardened plated main case, stainless-steel wear plates and a pair of patented gears with rubber lobes and stainless-steel wear surfaces. It is not known how long a pump with this combination of features will last, but speculation is that the pump will last at least five times if not 10 times as long as a standard rotary gear pump.

New organic products

Soil enhancers are creating new business for hydroseeding companies by applying products to existing lawns as well as new lawns. These products help replenish spent resources of poor soil, restoring it to a healthy, natural state. They are soluble in water and, with agitation, mix properly in hydroseeding equipment. For those of you who would rather have an organic lawn and who need that shot of health in your soil, this system is something that every hydroseeding contractor should consider using because they are approved for use on organic certified properties by the USDS National Organic Program (NOP). For an example of this system, check out the Organic Discussion Forum at www.soilsecrets.info or the Soil Secrets LLC, Web site at www.soilsecrets.com.

New drought-resistant technique

Droughts are a way of life in some parts of the country, evidenced by water rationing and brown yards. Now there is a polymer type of product that will help keep the lawn green and allow reduction in watering the lawn. This is a must for sandy soils that dry out too quickly and will be great for those lawns without a sprinkler system or hot-spots that dry out too soon. The water savings alone will pay for the extra cost.

This is a different type of polymer than the tackifier type. This is a cross-linked potassium-based polyacrylamide. When hydrated, it has the consistency of clear Jell-O. It comes in three granular sizes: small (0.8 to 1 mm), medium (1 to 2 mm) and large (2 to 4 mm). These polymers remain viable in the soil up to 10 years, depending on granular size and soil conditions. They will reduce irrigation requirements up to 50 percent and can reduce fertilizer requirements and runoff into lakes and streams.

Before planting, till into soil 5 pounds of polyacrylamide per 1,000 square feet. In existing lawns, you can aerate the soil and apply the polyacrylamide so it drops into the holes, as deep into the soil as possible.

One contractor, after doing this application, had the “water-police” called on his customer because his lawn was too green to be watered only once a week, as called for during the water rationing.

New herbicides can be added to hydroseeding mix

Look for new herbicides that work on bermudagrass, tall fescue, ryegrass, buffalograss and zoysiagrass by killing crabgrass and a long list of other weeds including clover and other broadleaf weeds. What is new about these products is that you can add them to your hydroseeding mix. One product I have come across is Drive 75 DF herbicide (containing the active ingredient quinclorac) by BASF Corporation, and it worked well on a bermudagrass application. You can make applications before, during and seven days or more after you germinate the seed. It also has an average of a 45-day residual effect. This helps when you find weeds germinated the day you are scheduled to plant or find competing weeds germinated with your lawn, allowing a clean-up while grass is still young. Some states require a commercial applicators license to use this product.

Glenn Young is the owner of A-1 HydroMulch (Tyler, Texas). He also was the founding vice president of the Hydro Turf Planters Association (1998), which dissolved in November 2004, and has been working in the hydroseeding industry for 24 years. You can visit his Web site at www.New-Grass.org.